The grass genera of the world
The grass genera of the world | |
Including Atractocarpa Franch.
Habit, vegetative morphology. Perennial (sometimes with root tubers); rhizomatous. The flowering culms leafless, or leafy (i.e. sometimes with separate fertile and vegetative culms). Culms herbaceous; unbranched above. Culm leaves present. Upper culm leaf blades fully developed. Culm internodes hollow. Rhizomes pachymorph. Plants unarmed. Leaves not basally aggregated; non-auriculate; without auricular setae. Leaf blades ovate-lanceolate; broad; 20–70 mm wide; flat; pseudopetiolate; cross veined; persistent. Ligule a fringed membrane. Contra-ligule present.
Reproductive organization. Plants bisexual, with bisexual spikelets; without hermaphrodite florets (the spikelets with proximal male florets and a terminal female).
Inflorescence. Inflorescence narrowly paniculate; contracted; espatheate, or spatheate (in that the branches are sometimes subtended by small bracts); not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes short ‘racemes’; persistent. Spikelets not secund; pedicellate; imbricate.
Female-fertile spikelets. Spikelets 12–15 mm long; lanceolate to ovate; compressed laterally; disarticulating above the glumes; not disarticulating between the florets (the males falling together with the terminal female); with distinctly elongated rachilla internodes between the florets (having a 1 mm internode beneath the female floret, bearing a fleshy outgrowth embracing the base of the floret). Rachilla terminated by a female-fertile floret (seemingly). Hairy callus absent.
Glumes two; very unequal, or more or less equal; shorter than the adjacent lemmas; ciliate on the margins; pointed (the upper), or not pointed; awnless; carinate; similar. Lower glume much shorter than half length of lowest lemma; 4 nerved, or 5 nerved. Upper glume 7 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 3–5; paleate. Palea of the proximal incomplete florets fully developed. The proximal incomplete florets male (the stamens 6, monadelphous, at least sometimes with penicillate anthers). The proximal lemmas lanceolate; awnless; 11 nerved; exceeded by the female-fertile lemmas.
Female-fertile florets 1. Lemmas convolute; decidedly firmer than the glumes; smooth; not becoming indurated (pallid, softly leathery below, becoming cartilaginous towards the apex); entire; blunt; awnless; hairy (except towards the tip); non-carinate (rounded on the back); without a germination flap; 9–11 nerved. Palea present; relatively long; convolute; entire; awnless, without apical setae (apically fringed); thinner than the lemma; not indurated (but cartilaginous towards the apex); several nerved (5 nerved in the material seen); keel-less (abaxially rounded). Palea back hairy. Lodicules present; 3; free; membranous; ciliate; not toothed. Stamens 0. Ovary glabrous; with a conspicuous apical appendage. The appendage broadly conical, fleshy (and very long). Styles fused (into one). Stigmas 2–3; brown.
Fruit, embryo and seedling. Hilum long-linear. Pericarp free. Embryo small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals much narrower); of similar wall thickness costally and intercostally (thin walled). Intercostal zones with typical long-cells. Mid-intercostal long-cells rectangular; having markedly sinuous walls (the sinuosity deep, rather irregular). Microhairs seemingly absent (none seen in either of the species examined). Stomata common. Subsidiaries non-papillate; dome-shaped to triangular (the triangles often apically truncated). Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies when properly developed crescentic and oryzoid-type. P. ciliata with abundant small microhairs and prickles intercostally. Costal zones with short-cells. Costal short-cells conspicuously in long rows. Costal silica bodies present and well developed; consistently saddle shaped.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade; with arm cells; with fusoids. The fusoids external to the PBS. Leaf blade adaxially flat. Midrib conspicuous; having complex vascularization (with an abaxial arc of three (a large median with small laterals) embedded in sclerenchyma, and a small adaxial sclerenchyma mass containing 1–3 small bundles); with colourless mesophyll adaxially. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans (these large and wide). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); forming ‘figures’ (I’s and ‘anchors’). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 12. 2n = 24. 2 ploid.
Taxonomy. Bambusoideae; Bambusodae; Puelieae.
Distribution, ecology, phytogeography. 6 species; tropical Africa. Shade species.
Paleotropical. African. Sudano-Angolan and West African Rainforest. South Tropical African.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting specified attributes, summaries of attributes within groups of taxa, geographical distribution, classification, and species sampled for anatomy.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. Version: 18th December 2012. http://delta-intkey.com’.